1. Field of the Invention
The present invention relates to an instrument capable of protecting a tip end portion of a writing or applying medium held in a holder by covering the tip end portion with a cap when not in use.
2. Description of the Related Art
Conventionally, in a writing instrument, for example, it is necessary to cover a tip end portion of a writing medium when it is not used in order to protect the tip end portion of the writing medium, to prevent a writing medium from being dried, or not to contaminate surroundings, and to this end, a cap is generally fitted onto a tip end portion of the holder to be attachable and detachable.
However, with the conventional cap, both hands have to be used to remove the cap, its attaching and detaching operation is troublesome, and it is feared that the removed cap is lost.
Therefore, Japanese Patent No. 2714780 proposes a capless writing instrument which can project and retreat a tip end writing portion with a knocking operation without a cap and includes a mechanism for preventing leakage, drying and backflow of ink. In this patent publication, a guide through which a front part of the writing medium can penetrate is provided inside a body of the writing instrument so as to be movable in a longitudinal direction and to restrain the forward movement of a specified amount or more, a seal lid of which inner surface is constituted by an elastic body is provided at a tip end of this guide so as to be openable and closable, and a string-shaped member is connected to the seal lid, so that the string-shaped member pulls the seal lid to closely attach the tip end of the writing medium to the elastic body of the seal lid when the writing medium is housed, and when the writing medium moves forward, pulling of the thread-shaped member is loosened to release the sealed state of the seal lid.
However, in the writing instrument described in the above-described patent, the stroke length advancing the writing medium to project it from the tip end of the body becomes long because it is necessary to provide a space for the seal lid to open and close inside the body.